In-Situ Cyclized Polyacrylonitrile as an Electron Selective Layer for n-i-p Perovskite Solar Cell with Enhanced Efficiency and Stability.

In situ cyclized polyacrylonitrile (CPAN) is developed to replace n-type metal oxide semiconductors (TiO2 or SnO2) as an electron selective layer (ESL) for highly efficient and stable n-i-p perovskite solar cells (PSCs). The CPAN layer is fabricated via facile in situ cyclization reaction of polyacrylonitrile (PAN) coated on a conducting glass substrate. The CPAN layer is robust and insoluble in common solvents, and possesses n-type semiconductor properties with a high electron mobility of 4.13×10-3 cm2 V-1 s-1. With the CPAN as an ESL, the PSC affords a power conversion efficiency (PCE) of 23.12 %, which is the highest for the n-i-p PSCs with organic ESLs. Moreover, the device with the CPAN layer holds superior operational stability, maintaining over 90 % of their initial efficiency after 500 h continuous light soaking. These results confirm that the CPAN layer would be a desirable low-cost and efficient ESL for n-i-p PSCs and other photoelectronic devices with high performance and stability.

Cyclized Polyacrylonitrile as a Promising Support for Single Atom Metal Catalyst with Synergistic Active Site.

Metal single atom catalysts (SAC) have been successfully used in heterogeneous catalysis but developing a scalable and economic support for SAC is still a great challenge. Here, cyclized polyacrylonitrile (CPAN) is proposed as a promising support for single atom metal catalysts. CPAN can be easily prepared from cheap industrial product polyacrylonitrile (PAN), which has excellent processability. A series of SAC on CPAN (M/CPAN, M = Ag, Cu, Ru) are designed and the catalytic activities of the as synthesized M/CPAN are investigated by the model reduction reaction of p-nitrophenol (4-NP). M/CPAN presents excellent catalytic performance with high stability and theoretical calculations elucidate that Ag/CPAN synergistically catalyze 4-NP reduction following the Langmuir-Hinshelwood (L-H) mechanism with 4-NP preferentially adsorbing at the Ag sites and H adsorbing at the bridge C sites. These results, for the first time, reveal that the single atom on CPAN can catalyze 4-NP reduction efficiently. This methodology provides a convenient route for the preparation of a variety of SAC, and this strategy is readily scalable and holds great potential in catalytic applications.

Large Area Millisecond Preparation of High-Quality, Few-Layer Graphene Films on Arbitrary Substrates via Xenon Flash Lamp Photothermal Pyrolysis and Their Application for High-Performance Micro-supercapacitors.

We report a method for fast, efficient, and scalable preparation of high-quality, large area, few-layer graphene films on arbitrary substrates via high-intensity pulsed xenon flash lamp photothermal pyrolysis of thin precursor films at ambient conditions in millisecond time frames. The precursors comprised poly(2,2-bis(3,4-dihydro-3-phenyl-1,3-benzoxazine)), and cyclized polyacrylonitrile and possess significant absorption cross section within the bandwidth of the emission spectrum of a xenon flash lamp. By localizing light absorption to the precursor films, the process enabled the preparation of few-layer graphene films on any substrate, including thermally sensitive substrates without the need for any catalytic substrate as in chemical vapor deposition-based approaches or conductive electrodes as in electrochemical method-based approaches. The extent of conversion of the precursor films to graphene was strongly dependent on pulse energy and the local temperature achieved due to photothermal effect, which were controlled via pulse power modulation; it also depended on structural properties of the precursor and to a lesser extent on the substrate. The cPAN showed a higher efficiency for conversion to graphene, as confirmed by Raman spectra (ID/IG ∼ 0.3), and sheet resistance of 0.1 Ω cm. To demonstrate the utility of the process, graphene film electrodes prepared photothermally on carbon fiber current collector were used for the fabrication of micro-supercapacitors with a very high areal supercapacitance of 3.5 mF/cm2. Subsequent deposition of manganese oxide onto the fabricated electrodes significantly increased the energy storage capability of the supercapacitor, yielding a device with exceptionally high capacitance of 80 F/g at 1 mA current, good rate capability, and long cycle life.

Application of Cyclized Polyacrylonitrile for Ultrafiltration Membrane Fouling Mitigation.

In this study, novel composites were produced by blending partially cyclized polyacrylonitrile (cPAN) and poly(amide-imide) (PAI) in N-methylpyrrolidone in order to fabricate asymmetric membranes via phase inversion method. The compatibility of PAI and cPAN through possible intermolecular interaction was examined by quantum chemical calculations. The composite membranes were characterized by FTIR, SEM, contact angle measurements, etc. A considerable reduction in the contact angles of water and ethylene glycol (EG) was observed after adding cPAN to the PAI membrane, which is evidence of improved membrane hydrophilicity. Membrane transport properties were investigated in ultrafiltration tests by measuring the pure water flux, rejection of proteins, and flux recovery ratio (FRR). The best properties were found for the membrane containing 5 wt% cPAN; an increase in BSA rejection and a remarkable increase in FRR were observed, which can be explained by the hydrophilization of the membrane surface provided by the presence of cPAN.

Free-Standing Stable Silicon-Based Anode with Exceptional Flexibility Realized by a Multifunctional Structure Design in Multiple Dimensions.

Cyclized polyacrylonitrile (cPAN) with decently flexible, elastic, and conductive properties is a promising substrate or binder material for flexible devices. However, it is infeasible to accommodate the large volume expansion and contribute the exceptional rate capability of silicon anodes in lithium-ion batteries only counting on the limited elasticity and conductivity of cPAN. Herein, we report a robust silicon/carbon-cPAN-graphene (SC-CP-G) composite membrane with excellent flexibility based on a multifunctional structure design in multiple dimensions, which can be used as a free-standing integrated anode for lithium ion batteries. In this integrated electrode, silicon nanoparticles are encapsulated in porous carbon with in situ formed confined space, and the silicon/carbon particles are further embedded in cPAN nanofibers, which are inextricably interwoven with a reduced graphene oxide film, forming an interpenetrating network architecture. The unique hierarchical and functional structure design greatly improves the mechanical performance, cycling stability, and capacity accessibility of silicon electrodes, delivering a specific capacity of 1847 mA h g-1 at 2 A g-1 and a capacity retention of 87% after 150 cycles.

ZnO/CPAN Modified Contact Lens with Antibacterial and Harmful Light Reduction Capabilities.

Compared with traditional glasses, the comfortable and convenient contact lens (CL) has seen an upsurge among the public. However, due to the lack of antibacterial properties of ordinary CLs, the risk of eye infection is greatly increased accordingly. On the other hand, ordinary CLs also cannot effectively reduce the short-wavelength blue light emitted from electronic products, such as mobile phones and computers. Aiming at the above two problems, zinc oxide (ZnO)/cyclized polyacrylonitrile (CPAN) composites are developed for CL modification. After loading with ZnO/CPAN (ZC), the CL shows a broad-spectrum antibacterial property. Further experiments also prove that it can block UVB, UVA, as well as blue light selectively, under the premise of ensuring hydrophilicity and certain transparency. Theoretically, this ZC-decorated CL can fundamentally reduce the damage to the eyes from harmful light emitted by light-emitting diodes and the secretion of pro-inflammatory factors, which is thus a promising eye protection strategy for modern society.

Enabling a High Performance of Mesoporous α-Fe2O3 Anodes by Building a Conformal Coating of Cyclized-PAN Network.

The mesoporous α-Fe2O3/cyclized-polyacrylonitrile (C-PAN) composite was synthesized by a rapid and facile two-step method. The electrode was fabricated without conductive carbon addictive and employed as anode for lithium-ion batteries. Results demonstrate that building a conformal coating of a C-PAN network can provide a strong adhesion with active materials and contribute excellent electronic conductivity to the electrode, which can relieve the huge volume changes during a lithiation/delithiation process and accelerate the charge transfer rate. The material exhibited high reversible capacity of ca. 996 mAh g(-1) after 100 cycles at 0.2C, 773 mAh g(-1) at 1C and 655 mAh g(-1) at 2C, respectively, showing well-enhanced cycling performance and superior rate capacity, and also exhibiting significantly improved power density and energy density compared to the traditional graphite materials. Our results provide a facile and efficient way to enhance the performance of α-Fe2O3 anode material, which also can be applied for other oxide anode materials.